1. Field of the Invention
The present invention relates to an apparatus for controlling backlight. More particularly, the present invention relates to an apparatus for controlling backlight, which is adapted for controlling a backlight module including a plurality of luminance-controlling blocks and is advantageous in significantly increasing the image contrast.
2. Description of Related Art
With the advancement of the modern video technology, liquid crystal or plasma displays have been widely used in display screen of consumer electronics products, such as cell phones, notebook computers, personal computers, and personal digital assistants (PDAs). However, since the panel of the liquid crystal or plasma display itself does not have light-emitting function, it is necessary to dispose a backlight source below the panel to provide display light source for the liquid crystal panel. Currently, backlight sources available in the market include plane fluorescent lamps, cold cathode fluorescent lamps (CCFLs), and light emitting diodes (LEDs). As LED has the advantages such as small volumes, free of thermal radiation, low power consumption, long life time, and preferred response speed, and is capable of solving many problems that plane fluorescent lamp and CCFL cannot overcome previously, thus being the backlight source has promising prospect at the present stage.
Taking liquid crystal panel as an example, in the current technique, LEDs serve as the backlight source of the liquid crystal panel in the manner of being full light or full dark. When displaying a frame, LEDs are in a state of being full light, and the liquid crystal panel determines the amount of the light passing through the liquid crystal panel through the rotation angle of the internal liquid crystal molecules. However, if the mount of the light passing through the liquid crystal panel is merely determined by the rotation angle of the liquid crystal molecules, the frame contrast will be limited by the scope of the rotation angle of the liquid crystal molecules, and thus the fineness of the frame is reduced. Additionally, when a part of area in the frame needs a lower luminance, LEDs still serve as the backlight source of the liquid crystal panel in the manner of being full light, thereby causing excessive power wastage.